LWS Fabry Perot spectrum of the HF J=2-1 line toward Sgr B2.
During the observation the ISO LWS beam had a FWHM diameter of 70". The flux has been normalised relative to the continuum flux of 4.8 x 104Jy. The LSR velocity plotted on the horizontal axis applies to the HF J=2-1 line at 121.6973 microns (D. Neufeld).
Full size image.
This observation has been discussed in the ESA Press Release;
and has been published in the Astrophysical Journal Letter;
"Discovery of Interstellar Hydrogen Fluoride", Neufeld, D. et al. ApJ Letters v.488, p.L141.